I found out what the deal : I edited the file with an external program and recorded in Unicode.

As against, I have always a problem with the trial version.
Until now, I could run edit text mode or create a DLL resource.
Since this morning, I have a message telling me that these functions are not part of the trial version.

The problem with Unicode RC file could be that your external editor didn't include BOM Unicode mark at the beginning of the file. So Resource Builder was unable to detect that it is Unicode.
As stated on http://www.resource-builder.com/download.html the trial version includes the following limitations:
1. Works only 30 days from first run.
2. Edit as text works only first 15 days.
3. Link to EXE and DLL creation work only first 15 days.

So it looks like it is past more than 15 days after your trial started and these functions stopped to work.